Messages in this thread |  | | Date | Thu, 17 Jan 2013 14:08:32 +0900 | From | Yasuaki Ishimatsu <> | Subject | Re: [PATCH v5 0/5] Add movablecore_map boot option |
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2013/01/17 7:52, H. Peter Anvin wrote: > On 01/16/2013 01:29 PM, Andrew Morton wrote: >>> >>> Yes. If SRAT support is available, all memory which enabled hotpluggable >>> bit are managed by ZONEMOVABLE. But performance degradation may >>> occur by NUMA because we can only allocate anonymous page and page-cache >>> from these memory. >>> >>> In this case, if user cannot change SRAT information, user needs a way to >>> select/set removable memory manually. >> >> If I understand this correctly you mean that once SRAT parsing is >> implemented, the user can use movablecore_map to override that SRAT >> parsing, yes? That movablecore_map will take precedence over SRAT? >> > > Yes, but we still need a higher-level user interface which specifies > which nodes, not which memory ranges, should be movable.
I thought about the method of specifying the node. But I think this method is inconvenience. Node number is decided by OS. So the number is changed easily.
for example:
o exmaple 1 System has 3 nodes: node0, node1, node2
When user remove node1, the system has: node0, node2
But after rebooting the system, the system has: node0, node1
So node2 becomes node1.
o example 2: System has 2 nodes: 0x40000000 - 0x7fffffff : node0 0xc0000000 - 0xffffffff : node1
When user add a node wchih memory range is [0x80000000 - 0xbfffffff], system has: 0x40000000 - 0x7fffffff : node0 0xc0000000 - 0xffffffff : node1 0x80000000 - 0xbfffffff : node2
But after rebooting the system, the system's node may become: 0x40000000 - 0x7fffffff : node0 0x80000000 - 0xbfffffff : node1 0xc0000000 - 0xffffffff : node2
So node nunber is changed.
Specifying node number may be easy method than specifying memory range. But if user uses node number for specifying removable memory, user always need to care whether node number is changed or not at every hotplug operation.
Thanks, Yasuaki Ishimatsu
> That is the > policy granularity that is actually appropriate for the administrator > (trading off performance vs reliability.) > > -hpa >
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